Resistance to Sweat

The protective performance of a sun protection product is assessed through its SPF, UPF and substantivity. A product’s substantivity is defined as its ability to bind to the skin and resist removal. In the case of suncare products, this generally involves assessing resistance to water, sand or rubbing against fabrics. However, unlike the elements involved in exposure above the sun protection film, sweat is released below the sun protection film to ensure thermoregulation of the body, during physical activity or in high temperatures.

Under these conditions, customers are usually also exposed to the sun, so sun protection must be intact. In order to determine and substantiate this claim of product efficacy, WENEOS has developed an exclusive in vitro method which requires the measurement of a sun protection factor (SPF) before and/or after exposure to sweat.

days for an in vitro study with a final report

solar studies carried out


compliance with solar standards


We can assess the sun protection of your products in full compliance with official methods, or claim the properties of your products through exclusive tests developed by WENEOS.

Sweat resistance in vitro

WENEOS has developed a new perspiration simulator to assess the in vitro perspiration resistance of a sunscreen product.

Thus, using a spectrophotometric in vitro method, products can be exposed to an artificial sweat solution under a set of specific conditions (flow rate, exposure time, orientation, etc.). Next, the percentage of perspiration resistance is obtained by calculating the ratio of the sun protection factor (SPF) before and after exposure for each condition. Finally, to be declared perspiration-resistant, this percentage must be greater than 50% for both conditions tested.

(ref. HeSWEAT)

Published method: In progress


To optimize your suncare products or check their quality, we offer you exclusive tests developed by WENEOS.

Comparison of in vitro signal absorbance measurements with resistance (batch, aging, etc.)

La méthode de comparaison statistique permet de comparer deux produits de protection solaire en termes de vieillissement, de lot, de benchmarck, etc. Sur la base de tout contrôle du spectre d’absorbance entre une référence et un produit à tester au moyen d’une méthode in vitro, deux règles importantes sont respectées . Tout d’abord, comparez en même temps et dans les mêmes conditions les deux produits pour limiter la variabilité des mesures. Deuxièmement, une vérification en trois étapes basée sur les valeurs d’absorbance, y compris la comparaison de la forme des courbes, de la variabilité et de l’intensité.

Dans cette méthode, une étape spécifique pour comparer la résistance des deux produits peut être ajoutée telle que la résistance à l’eau, la résistance au frottement, etc.

(réf. HeCOMP-2)

Méthode publiée : *In vitro comparison – A new accessible and reliable statistical method to compare the global UV protection properties of cosmetics – Lutz and S. Miksa, H&PC Sun Care, July/August 2013 | *Sunscreen products: Some practical applications for a new comparison test method to help Development and ensure Quality Controls – D. Lutz, S. Miksa and C. Guy, H&PC Today, November/December 2014

Discover the analyses additionalfor all-round sun protection

UV protection

  • SPF – UVB
  • UVA:UVB ratio
  • Photostability
  • Absorbance spectrum

Beyond UV

  • Ultra-Long UVA
  • Blue Light
  • Visible
  • Infrared
  • Full Spectrum
  • UVC


  • Water resistance
  • Sweat resistance
  • Sand resistance
  • Rub resistance
  • Wet Skin Application
  • Extreme conditions
  • Persistence | Long-lasting
  • Immediate protection